The present invention relates to a unique well pumping system which is simple in construction, less costly, and more efficient than well pumping systems typically used in the prior art.
Conventional well pumping systems utilizing submersible pump devices typically include an above ground pumping unit, downhole tubing, a sucker rod string or a relatively large diameter centrifugal pump, usually 25 to 300 HP, and a relatively large electric or other motor to drive the pump. Systems of this type are fairly common, and not only are they difficult and expensive to install and service, but pump efficiencies are in the relatively low 30% to 50% range.
The present invention provides a process and apparatus which overcome many disadvantages of the prior art systems.
The well pumping system of this invention includes a submersible pump and motor assembly suspended within a well casing from the wellhead. This is accomplished with the aid of a flexible, hollow tube, preferably in the form of 1.25" O.D. conventional metal coil tubing attached at its upper end to the wellhead and at its downhole end to pump and motor assembly. Within, and shielded by, the metal coil tubing is an electrical power cable providing power to the pump and motor assembly. The arrangement is such that the pump and motor assembly is suspended by the coil tubing, not the power cable, and thus is easily lowered into, and lifted out of the well casing with no stress on the power cable itself.
In accordance with this invention, fluid such as water or oil, is pumped out of the well within a substantially annular space between the metal coil tubing and the power cable.
This invention thus eliminates a number of prior art components, such as the above ground pumping unit, downhole tubing, sucker rod string, downhole conventional pump, polish rod, and stuffing box.
All of the prior art components have been replaced by a flexible string of conventional metal coil tubing; a string of two or three wire braided cable, preferably clad with a suitable plastic such as polypropylene; a relatively small (about 1 to 10 HP) motor; and a relatively small (2.75 inch diameter) gear or piston pump.
Because of the elimination of several of the heavier, more cumbersome components of the prior art, and particularly the sucker rod string, smaller motors and pumps may be used at higher efficiencies up to 95%.
The present invention has the following additional advantages:
(1) service life of pump is increased; PA0 (2) reduced repair and maintenance costs; PA0 (3) reduced installation time and cost; PA0 (4) ability to locate pump and motor assemblies in crooked or curved well casings; PA0 (5) better performance in gas locking environments; PA0 (6) fewer safety related hazards; PA0 (7) more attractive appearance at the ground level by reason of a significantly smaller wellhead; PA0 (8) ability to monitor downhole fluid levels and associated means to shut down system when fluid levels are low. PA0 (a) providing hollow, flexible tubing having length approximately the depth of the well; PA0 (b) inserting an electrical cable within said tubing, said cable and tubing sized to create a substantially annular space between said wire and said tubing; PA0 (c) attaching said electrical wire and said tubing to a submersible motor and pump assembly; PA0 (d) lowering said pump and motor assembly into said well casing; and PA0 (e) pumping said fluid out of the well casing in the annular space between the electrical wire and the flexible tubing.
In a related aspect, a process of installing a well pumping system is provided, which includes the steps of: